This invention is related to the fully passive-type solar lumber drying house H which is a hot house made up by improving an agricultural vinyl-house in which the stacked lumber is dried due to solar energy collected passively, then moist air yielded when drying the lumber is exhausted passively through an insulated cylinder 10.
Up to this time, an artificial lumber drying has been carried out applying rapid drying technique, under the high temperature over 100° C. and due to rapid drying method which is able to dry out for three or four days and because of deformation of the lumber and appearance of cracks and flaws on the lumber surface, a quality of the lumber production dried is not so good.
Up to this time, the solar lumber drying method utilized is related into two types that a fully active-type solar lumber drying house which collects actively solar energy and an active passive-type solar lumber drying house which collects solar energy actively in a partial part and passively in a most part have been developed.
(a) The former case is related to a typical active-type solar lumber drying house, that a large solar collector of 120 m2 area in which a porous sheet is inserted as collecting material is put on a roof of the drying house made of wood to collect solar energy actively using a large fan, and then hot air warmed by which is introduced into and circulated within the drying house forcefully by the other large fans to dry out the lumber (Japanese Published Unexamined Patent Application No. 63-70048).
Applying this apparatus which was cost comparable in that time, net volume 11 m3 of needle-leave tree could be dried out from 45% to below 20% for nine days, however the electric power consumption was too much to spread widely the technique over the area in this country and over seas.
(b) The latter case is related to an active passive-type solar lumber drying house that a handmade solar lumber dryer constructed with wooden frame and transparent plate had been made and spread in some area of Hokkaido twenty years ago because of cheap and simple structure (T. Norota, et al., Report of the Hokkaido Forest Products Research Institute, No. 72, March 1983, P96-124).
(c) Another case defined to the latter is a lumber drying house supplying latent regional energy as a heat source, for example solar energy and hot water from a spring, to make the house-build lumber of larch with high quality under low temperature drying. In the large log-house made of larch and covered by transparent film, from the roof of which a large boxy sack made of transparent film is hanged from the roof like a mosquito net, in which several groups of the lumber mounted on a trolley placed on the floor can be dried using solar energy and auxiliary heat from a floor heater, through fan-cons with heat exchanger and small fans. (Japanese Patent No. 3577483)